DNA, the strings of chemicals which define us, acts like a kind of read-only biological data storage device. Now, though, synthetic biologists have managed to turn DNA into a form or rewritable memory, just like that in our computers.

While it's not the first rewritable biological storage system to be made—others have used proteins which bond to DNA to perform a similar function—it is the first time such an effect has been achieved in the DNA itself, and it could make synthetic digital cells a possibility.

To achieve it the researchers, from Stanford University, spliced genetic elements from a bacterium-infecting virus into the DNA of Escherichia coli. What they were left with is a system which contains a stretch of DNA flanked by sites which indicate to enzymes that the DNA can be "cut" and then "pasted" in reverse orientation—and that's just what happens. In fact, the process can be performed over and over, with the team so far demonstrating that is can be done at least 16 times.

"It's a pretty sad criticism of the state of technology in synthetic biology where we're trying to program the expression of half a dozen genes and it takes 750 design attempts to get that working. It's like trying to write a six-line code on a computer that takes 750 debug attempts to work."

But even though it took so long to get, right, it's a big achievement. Eric Klavins, of the University of Washington in Seattle, explains to Nature why the finding is so interesting:

"What Drew's group can do that others haven't demonstrated is the ability to cycle the memory element over and over, kind of like you can write a bit to a hard drive, read it and change it back over and over again."

Indeed, the whole point of this research is to create biological, digital storage devices that can be employed within synthetic biological systems. While rewritable DNA storage will probably never power your hard drive, it might be in living creatures before your lifetime is through. [PNAS via Nature]